The present invention relates to an apparatus for determining a reference position of a movable member. The apparatus is adapted to deliver a logical electrical signal when the member passes through the reference positions.
The invention is applicable particularly, but not exclusively, to the case of a robot arm constituted by several sections which are movable with respect to each other and of which the end section carries a tool, the arm being controlled by a computer. It is applicable more especially to the case where the data concerning the displacements of the sections of the arm delivered by incremental transducers which deliver one electrical pulse each time an increment of movement is effected. It is clear that, if the incremental transducers are capable of so delivering displacement data, they cannot provide positional data without a reference position which defines the origin of the displacement.
The present invention makes it possible to provide an electrical signal which furnishes this reference position in a form that is easily compatible with the incremental displacement signals.